Concurrency

Java Concurrency in Practice contains an excellent treatment of the issues. In a dynamic environment such as OSGi you need to be aware of the rules surrounding things such as visibility, safe publication etc.

Concurrency: Past and Present by Brian Goetz -- A 1h presentation on Concurrency in Java. Brian shows a very simple example and how difficult it is to get concurrency done correctly. If you think threading is easy -- listen to this talk... If you are interested in alternatives and future skip the first 30 min (the 30 min are just showing why threading (using locks) is difficult).